As is well known to those skilled in the art, it is desirable to convert heavy hydrocarbons, such as those having a boiling point above about 1000.degree. F., into lighter hydrocarbons which are characterized by higher economic value. It is also desirable to treat hydrocarbon feedstocks, particularly petroleum residues, to achieve other goals including hydrodesulfurization (HDS), hydrodenitrogenation (HDN), carbon residue reduction (CRR), and hydrodemetallation (HDM)--the latter particularly including removal of nickel compounds (HDNi) and vanadium compounds (HDV).
These processes typically employ hydrotreating catalysts with specified ranges of pores having relatively small diameters (i.e. micropores) and pores having relatively large diameters (i.e. macropores).
U.S. Pat. No. 5,047,142 (Dai et al.) discloses a catalyst composition useful in the hydroprocessing of a sulfur- and metal-containing feedstock comprising an oxide of nickel or cobalt and an oxide of molybdenum deposited on a porous alumina support in such a manner that the molybdenum gradient of the catalyst has value of less than 6.0 and 15-30% of the nickel or cobalt is in an acid extractable form, and having a surface area of 150-210 m.sup.2 /g, a Total Pore Volume (TPV) of 0.50-0.75 cc/g, and a pore size distribution such that less than 25% TPV is in pores having diameters of less than 100 .ANG., 70.0-85.0% TPV is in pores having diameters of 100 .ANG.-160 .ANG. and 1.0-15.0% TPV is in pores having diameters of greater than 250 .ANG..
U.S. Pat. No. 4,941,964 (Dai et al.) discloses a process for the hydrotreatment of a sulfur- and metal-containing feed which comprises contacting said feed with hydrogen and a catalyst in a manner such that the catalyst is maintained at isothermal conditions and is exposed to a uniform quality of feed, the catalyst comprising an oxide of a Group VIII metal, an oxide of a Group VIB metal and 0-2.0 weight % of an oxide of phosphorus on a porous alumina support and having a surface area of 150-210 m.sup.2 /g and a Total Pore Volume (TPV) of 0.50-0.75 cc/g, such that 70-85% TPV is in pores having diameters of 100 .ANG.-160 .ANG. and 5.5-22.0% TPV is in pores having diameters of greater than 250 .ANG..
U.S. Pat. No. 4,738,944 (Robinson et al.) discloses a catalyst composition useful in the hydrotreatment of hydrocarbon oils, the catalyst containing nickel and phosphorus and about 19-21.5% Mo (calculated as the oxide) on a porous refractory oxide having a narrow pore size distribution wherein at least 10% TPV is in pores having diameters less than 70 .ANG., at least 75% TPV is in pores having diameters between 50-110 .ANG., at least 60% TPV is in pores having diameters within about 20 .ANG. above and below the average pore diameter; and at most 25% TPV, most preferably less than 10% TPV, is in pores having diameters greater than 110 .ANG..
U.S. Pat. No. 4,652,545 (Lindsley et al.) discloses a catalyst composition useful in the hydroconversion of heavy oils, the catalyst containing 0.5-5% Ni or Co and 1.8-18% Mo (calculated as the oxides) on a porous alumina support, having 15-30% of the Ni or Co in an acid extractable form, and further characterized by having a Total Pore Volume (TPV) of 0.5-1.5 cc/g with a pore diameter distribution such that (i) at least 70% TPV is in pores having 80-120 .ANG. diameters, (ii) less than 0.03 cc/g of TPV is in pores having diameters of less than 80 .ANG., and (iii) 0.05-0.1 cc/g of TPV is in pores having diameters of greater than 120 .ANG..
U.S. Pat. No. 4,395,328 (Hensley, Jr. et al.) discloses a process for the hydroconversion of a hydrocarbon stream containing asphaltenes and a substantial amount of metals, comprising contacting the stream (in the presence of hydrogen) with a catalyst present in one or more fixed or ebullating beds, the catalyst comprising at least one metal which may be a Group VIB or Group VIII metal, an oxide of phosphorus, and an alumina support, where the alumina support material initially had at least 0.8 cc/gm of TPV in pores having diameters of 0-1200 .ANG., and at least 0.1 cc/gm of TPV in pores having diameters of 1200-50,000 .ANG.. The support material was heated with steam to increase the average pore diameter of the catalyst support material.
U.S. Pat. No. 4,341,625 (Tamm) discloses a process for hydrodesulfurizing a metal-containing hydrocarbon feedstock which comprises contacting the feedstock with a catalyst comprising at least one hydrogenation agent (i.e. Group VIB or Group VIII metal or combinations thereof) on a porous support, the catalyst being further characterized by having a TPV of 0.5-1.1 cc/g with at least 70% TPV in pores having diameters of 80-150 .ANG. and less than 3% TPV in pores having diameters greater than 1000 .ANG..
U.S. Pat. No. 4,328,127 (Angevine et al.) discloses a catalyst composition for use in the hydrodemetallation-desulfurization of residual petroleum oils, the catalyst comprising a hydrogenating component (i.e. Group VIB or Group VIII metal, or combinations thereof) on a porous support, further characterized by having a TPV of 0.45-1.5 cc/g with 40-75% TPV in pores having diameters of 150-200 .ANG., and up to 5% TPV in pores having diameters of greater than 500 .ANG..
U.S. Pat. No. 4,309,278 (Sawyer) discloses a process for the hydroconversion of a hydrocarbon feedstock comprising contacting the feedstock with hydrogen and a catalyst in a fixed bed, moving bed, ebullated bed, slurry, disperse phase, or fluidized bed reactor, where the catalyst comprises a hydrogenation component (i.e. Group VIB or Group VIII metal) on a porous support, and is further characterized by having a TPV of 1.0-2.5 cc/g with no more than 0.05-0.20 cc/g of TPV in pores having diameters of greater than 400 .ANG..
U.S. Pat. No. 4,305,965 (Hensley, Jr. et al.) discloses a process for the hydrotreatment of a hydrocarbon stream comprising contacting the stream with hydrogen and a catalyst, the catalyst comprising chromium, molybdenum, and at least one Group VIII metal on a porous support, further characterized by having a TPV of 0.4-0.8 cc/g with 0-50% TPV in pores having diameters smaller than 50 .ANG., 30-80% TPV in pores having diameters of 50-100 .ANG., 0-50% TPV in pores having diameters of 100-150 .ANG., and 0-20% TPV in pores having diameters greater than 150 .ANG..
U.S. Pat. No. 4,297,242 (Hensley, Jr. et al.) discloses a 2-stage process for the catalytic hydrotreatment of hydrocarbon streams containing metal and sulfur compounds, the process comprising: (i) first contacting the feedstock with hydrogen and a demetallation catalyst comprising a Group VIB and/or Group VIII metal; and (ii) thereafter reacting the effluent with a catalyst consisting essentially of at least one Group VIB metal on a porous support, having a TPV of 0.4-0.9 cc/g and a pore size distribution such that pores having diameters of 50-80 .ANG. constitute less than 40% TPV, pores having diameters of 80-100.degree. constitute 15-65% TPV, pores having diameters of 100-130 .ANG. constitute 10-50% TPV, and pores having diameters of greater than 130 .ANG. less than 15% TPV.
U.S. Pat. No. 4,089,774 (Oleck et al.) discloses a process for the demetallation and desulfurization of a hydrocarbon oil comprising contacting the oil with hydrogen and a catalyst, the catalyst comprising a Group VIB metal and an iron group metal (i.e. iron, cobalt, or nickel) on a porous support, having a surface area of 125-210 m.sup.2 /g and TPV of 0.4-0.65 cc/g with at least 10% TPV in pores having diameters less than 30 .ANG., at least 50% of pore volume accessible to mercury being in pores having diameters of 30-150 .ANG., and at least 16.6% of pores accessible to mercury being in pores having diameters greater than 300 .ANG..
U.S. Pat. No. 4,082,695 (Rosinski et al.) discloses a catalyst for use in the demetallation and desulfurization of petroleum oils, the catalyst comprising a hydrogenating component (i.e. cobalt and molybdenum) on a porous support, having a surface area of 110-150 m.sup.2 /g and a pore size distribution such that at least 60% of TPV is in pores having diameters of 100-200 .ANG. and not less than 5% TPV is in pores having diameters greater than 500 .ANG..
U.S. Pat. No. 4,066,574 (Tamm) discloses a catalyst composition useful in the hydrodesulfurization of a hydrocarbon feedstock containing organometallic compounds, the catalyst comprising Group VIB and Group VIII metal components on a porous support, having a TPV of 0.5-1.1 cc/g with a pore diameter distribution such that at least 70% TPV is in pores of diameters of 80-150 .ANG. and less than 3% TPV is in pores having diameters greater than 1000 .ANG..
U.S. Pat. No. 4,051,021 (Hamner) discloses a catalytic process for the hydrodesulfurization of a hydrocarbon feed which comprises contacting the feed with hydrogen and a catalyst, the catalyst comprising a Group VIB and Group VIII metal on a porous support, having a TPV of 0.3-1.0 cc/g with a pore diameter distribution such that greater than 50% TPV is in pores of diameters of 70-160 .ANG., and pores having diameters below 70 .ANG. and above 160 .ANG. are minimized.
U.S. Pat. No. 4,048,060 (Riley) discloses a two-stage process for hydrodesulfurizing a heavy hydrocarbon feed which comprises: (i) contacting the feed with hydrogen and a first catalyst to produce a first hydrodesulfurized hydrocarbon product, the first catalyst comprising a Group VIB and Group VIII metal on a porous support having a mean pore diameter of 30-60 .ANG.; and (ii) contacting the first hydrodesulfurized hydrocarbon product with hydrogen and a second catalyst under hydrodesulfurization conditions, the second catalyst comprising a Group VIB and Group VIII metal on a porous support further characterized by having a TPV of 0.45-1.50 cc/g with 0-0.5 cc/g of TPV in pores having diameters greater than 200 .ANG., 0-0.05 cc/g of TPV in pores having diameters below 120 .ANG., and at least 75% TPV in pores having diameters .+-.10 .ANG. of a mean pore diameter of 140-190 .ANG..
U.S. Pat No. 3,876,523 (Rosinski et al.) discloses a process for the demetallizing and desulfurizing of residual petroleum oil comprising contacting the oil with hydrogen and a catalyst, the catalyst comprising a Group VIB and Group VIII metal on a porous support having a pore size distribution such that greater than 60% TPV is in pores having diameters of 100-200 .ANG., at least 5% TPV is in pores having diameters greater than 500 .ANG., 10% TPV or less is in pores having diameters less than 40 .ANG., and the surface area of the catalyst is 40-150 m.sup.2 /g.
U.S. Pat. No. 3,770,617 (Riley et al.) discloses a process for the desulfurization of a petroleum hydrocarbon feed comprising contacting the feed with hydrogen and a catalyst, the catalyst comprising a Group VIB or Group VIII metal on a porous support having greater than 50% TPV in pores of 30-80 .ANG., less than 4% TPV in pores having diameters 200-2000 .ANG., and at least 3% TPV in pores having diameters greater than 2000 .ANG..
U.S. Pat. No. 3,692,698 (Riley et al.) discloses a catalyst useful in hydroprocessing of heavy feed stocks, the catalyst comprising a mixture of Group VIB and Group VIII metals on a porous support and having a pore size distribution such that a major portion of its TPV is in pores of diameters ranging from 30-80 .ANG., less than 4% TPV is in pores of diameters of 200-2000 .ANG., and at least 3% TPV is in pores of diameters greater than 2000 .ANG..
U.S. Pat. No. 4,746,419 (Peck et al) discloses catalyst compositions characterized by the presence of 0.1-0.3 cc/g in pores having diameter greater than 1200 .ANG. and no more than 0.1 cc/g of its pore volume in pores having diameter greater than 4000 .ANG..
Early petroleum distillate hydrotreating catalysts generally were monomodal catalysts with very small micropore diameters (for example, less than 100 .ANG.) and rather broad pore size distributions. First generation petroleum resid hydrotreating catalysts were developed by introducing a large amount of macroporosity into a distillate hydrotreating catalyst pore structure to overcome the diffusion resistance of large molecules. Such catalysts, which are considered fully bimodal HDS/HDM catalysts, are typified by U.S. Pat. Nos. 4,395,328 and 4,089,774 supra.
Another approach to developing improved catalysts for petroleum resid processing has involved enlarging the micropore diameters of essentially monomodal catalysts (having no significant macroporosities) to overcome the above described diffusion limitations. Essentially monomodal catalysts with small micropore diameters and low macroporosities designed for improved petroleum resid HDS include those disclosed in U.S. Pat. No. 4,738,944; 4,652,545; 4,341,625; 4,309,378; 4,306,965; 4,297,242; 4,066,574; 4,051,021; 4,048,060 (1st stage catalyst); 3,770,617; and 3,692,698, supra. Essentially monomodal catalysts with larger micropore diameters and low macroporosities designed for improved petroleum resid HDM include those disclosed in U.S. Pat. Nos. 4,328,127; 4,309,278; 4,082,695; 4,048,060 (2nd stage catalyst); and 3,876,523, supra.
A recent approach to developing improved catalysts for petroleum resid processing has involved the use of catalysts having micropore diameters intermediate between the above described monomodal HDS and HDM catalysts, as well as sufficient macroporosities to overcome the diffusion limitations for petroleum bottoms HDS (i.e., sulfur removal from hydrocarbon product of a hydrotreated petroleum resid having a boiling point greater than 1000.degree. F.) but limited macroporosities to limit poisoning of the interiors of the catalyst particles. Catalysts, with micropore diameters intermediate between the above-described monomodal HDS and HDM catalysts with limited macroporosities include those of U.S. patent application Ser. Nos. 168,095 (now U.S. Pat. No. 4,941,964); and 194,378 (now U.S. Pat. No. 5,047,142 supra).
However, none of the above-identified catalyst types has been found to be effective for achieving desired levels of hydroconversion of feedstocks components having a boiling point greater than 1000.degree. F. to products having a boiling point less than 1000.degree. F. while simultaneously yielding a 1000.degree. F.+ product having a lower sulfur content.
It is a particular feature of the prior art, however, that it has not heretofore been possible to carry out hydrotreating of such feedstocks to attain desirable results as measured by conversion without undesirable formation of sediment material as measured by the toluene insolubles test. The charge to hydrotreating is typically characterized by a very low toluene insolubles content of 0.02 wt % max.
Toluene insolubles sediment is measured by extracting the sample with toluene as outlined in IP-143 (standard methods for analysis and testing of petroleum products). Typical prior art hydrotreating processes commonly yield toluene insolubles of about 0.17 wt % and as high as about 0.8 wt % in the 1000.degree. F..sup.+ product. Production of large amounts of toluene insolubles is undesirable in that it results in deposition in downstream units which in due course must be removed. This of course requires that the unit be shut down for an undesirably long period of time.
It is an object of this invention to provide a process for hydrotreating a charge hydrocarbon feed containing components boiling above 1000.degree. F. Other objects will be apparent to those skilled in the art.